MHRA Approves the World's First Low-Carbon Asthma Inhaler

The inhaler in a patient's pocket is about to get a quieter kind of upgrade. On 21 July 2026, the UK's Medicines and Healthcare products Regulatory Agency approved a variation letting Chiesi Limited sell Clenil Modulite — its beclometasone dipropionate pressurised metered-dose inhaler, at 100 and 200 microgram strengths — reformulated with a new propellant, HFA-152a. MHRA and Chiesi both describe it as the first authorisation anywhere of a pMDI using that propellant.

Why a propellant swap needs a regulator at all

A pressurised metered-dose inhaler's propellant is not an active ingredient, but it is the mechanism that delivers a metered dose of medicine to the lungs — change it and the device's spray force, particle size distribution, and drug deposition can all shift with it. That is why swapping HFA-134a for HFA-152a is a regulatory event, not just a manufacturing change: the sponsor has to show the reformulated product still delivers beclometasone the way the original did. Chiesi built that case on a clinical development program comparing the HFA-152a and HFA-134a formulations, including a Phase III equivalence study, and MHRA's approval reflects that the two are considered therapeutically equivalent. The mechanism it used to approve the change — a variation to Chiesi's existing marketing authorisation, rather than a new application — is itself the regulatory precedent other sponsors will watch: it establishes that a propellant reformulation demonstrated on equivalence grounds can go through as a variation rather than a ground-up resubmission.

The number driving the switch

HFA-134a is a hydrofluorocarbon with a high global warming potential, and pMDIs are one of the few remaining medical uses of high-GWP HFCs at scale — a fact that has put them on a collision course with the Kigali Amendment's phase-down of HFC production and the UK and EU's own F-gas rules. HFA-152a is positioned as the industry's answer: a non-PFAS propellant with a substantially lower global warming potential than HFA-134a. Chiesi's own figure for the beclometasone products is direct — a carbon footprint cut of up to 90 percent compared with the current propellant. Ralph Blom, general manager of Chiesi UK and Ireland, put the approval in the context of the company's broader portfolio: “Beclometasone (100mcg and 200mcg) are the first in Chiesi's pMDI portfolio to transition to a low-GWP propellant — a significant milestone as we evolve our respiratory portfolio and advance towards our Net Zero by 2035 goal.”

MHRA's framing, and what stays the same for patients

• Safety framing: Julian Beach, MHRA's executive director of healthcare quality and access, said, “Keeping patients safe and enabling their access to high-quality, safe and effective medicines are key priorities for us.”
• No forced switch: current HFA-134a versions of Clenil Modulite continue to be available alongside the new formulation once it launches, so prescribers retain device choice during the transition rather than a hard cutover.
• Timing: the reformulated inhalers are expected in the UK later in 2026 — MHRA's approval is a green light for launch, not an announcement that the new device is on pharmacy shelves yet.
• Scope: the approval covers Chiesi's beclometasone-only Clenil Modulite line specifically; it does not itself extend to combination inhalers or other manufacturers' products, though Chiesi and competitors have parallel low-GWP programs in development for those.

What it signals beyond one product

For regulatory teams working on respiratory CMC, the significance is less the single product than the pathway. This is the first live example of a major inhaler manufacturer taking a propellant reformulation through to approval anywhere in the world, and MHRA's willingness to treat it as a variation on equivalence data sets a template other sponsors — and other regulators, including the EMA and FDA, who will each need their own submissions before HFA-152a products can launch in their markets — will be measured against as the rest of the industry's own low-GWP inhaler programs reach the filing stage.